Cosmetic products which improve the appearance of skin are increasingly popular with consumers. Frequently, consumers seek to alleviate or delay the signs of aged or photoaged skin, such as fine lines and wrinkles, dry and sagging skin. Consumers also frequently seek other benefits in addition to anti-aging.
A frequent, undesirable skin condition is "oily skin," the condition which results from the excessive amount of sebum on the skin. Sebum is skin oil which is produced by sebocytes (cells of the sebaceous glands in the skin) and is then secreted to the skin surface. Oily skin is associated with a shiny, undesirable appearance and a disagreeable tactile sensation. Oily skin affects various age groups.
Formation of free radicals in the skin does not appear to be related to the sebum secretion. Low levels of free radicals are formed in the skin as part of the natural metabolic pathways. The level of free radicals is increased in response to UV radiation and other environmental oxidants, e.g. pollution and cigarette smoke. Increased concentration of free radicals leads to lipid peroxidation in skin cells and cellular damage, which in turn results in a premature ageing of the skin with an accompanying loss of firmness and elasticity, wrinkles, discoloration, age spots, and dryness. Antioxidants, such as vitamin E (alpha-tocopherol), decrease the level of free radicals in the skin.
Cosmetic actives which provide more than one benefit are highly desirable, both from the manufacturer's and consumer's perspective. Especially valuable are compounds which are able to provide more than two cosmetic benefits.
U.S. Pat. No. 2,116,347 (Grether et al.) describes salicyloxy carboxy acid esters for external treatment of rheumatism. The Grether compounds differ from methoxycinnamyloxysalicylate employed herein at least in that the Grether compounds contain an ester group in place of a terminal carboxy group. Thus, the Grether compounds contain two ester bonds, whereas the compounds included in the present invention contain only one ester bond. Furthermore, the Grether compounds are aliphatic esters of salicylic acid, whereas the present ester is with an aromatic compound, methoxy cinnamic acid.
PCT application WO 93/10755 reports salicylic acid as an effective anti-wrinkling agent. Leveque et al. (U.S. Pat. No. 5,262,407) reports use of certain ring acylated salicylic acid derivatives as a treatment against skin aging. Ring alkylated salicylic acid has been reported in Japanese Patent 4036238 (Takasago Perfumery KK) for treatment of acne vulgaris. European Patent Application 0676194 (Roussel Uclaf) discloses cosmetic compositions for treatment of skin aging problems, the compositions containing salicylic acid or esters thereof. Salicylic acid esters disclosed in EP0676194 are non-ring esterified salicylic acid ester, i.e. salicylic acid is covalently bound via an ester bond to an alkyl chain or isopropylbenzyl.
E. Graf, "Anti-oxidant Potential of Ferulic Acid," Free Radical Biology and medicine, vol. 13, pp. 435-48, 1992 discloses that ferulic acid may photoprotect the skin when used in cosmetic lotions.
None of the art described above discloses methoxycinnamyloxy salicylate included in the present invention. Methoxycinnamyloxy salicylate is salicylic acid covalently bound via an ester bond to methoxycinnamic acid (a.k.a. ferulic acid). Methoxycinnamyloxy salicylate may also be called "ferulyl salicylate." It has been found, as part of the present invention that an ferulic acid or salicylic acid when employed individually do not significantly reduce sebum secretion, whereas ferulyl salicylate employed in the present invention attains significant reduction in sebum secretion. Furthermore, the use of ferulyl salicylate is advantageous compared to using a physical mixture of salicylic acid and ferulic acid: ferulyl salicylate is easier to formulate with, since ferulic acid and salicylic acid individually carry a greater number of incompatibilities than a single molecule of ferulyl salicylate.